To gather together the continuously conveyed rings of wire rod into coils, conventionally the wire rod 1 leaving the finishing mill 2 is cooled by a water cooler 2 and formed into continuous rings by a laying cone 4, thence the rings are conveyed by a conveyer 5 and dropped into a gathering tub 6, as illustrated in FIGS. 1 and 2.
Inside the gathering tub 6 is set a coil plate 8, shown in its highest position A-A in FIG. 2b, to receive each ring of the falling rod 1. The rings of the rod 1 are coiled around a rectangular pillar-like core, called a sail 7, vertically projecting through the center of the coil plate 8. As the rings of the rod 1 fall thereon, the coil plate 8 beings to descend until it eventually stops in the lowest position B-B.
When the piled up rings have reached a predetermined quantity, the wire rod 1 is cut to leave a separate coil 9 on the coil plate. As the sail 7 moves horizontally in direction H, the coil 9 is transferred from within the gathering tub 6 into a down-ender 14. When the coil 9 has been completely accommodated in the down-ender 14, the sail 7 descends and, then, moves empty, horizontally, back to the gathering tub 6 leaving the coil 9 in the down-ender 14. On completing the horizontal travel, the sail 7 rises into the original position shown in FIG. 2b.
The down-ender 14 tilts down, as indicated by the arrow D in FIG. 2b, and the coil 9 contained therein is placed in a horizontal position and pushed onto a hanger 15. Loaded on the horizontal bar of the hanger 15, the coil 9 is carried to a tying machine via an inspection process, both not shown. This rod-ring gathering and conveying method of the conventional type has some drawbacks as follows:
When the horizontal cross section of the sail is rectangular as shown in FIG. 2, the coil formed therearound tends to become elliptical rather than circular; i.e. the inside diameter becomes greater along the longer side of the sail than along the shorter side (see a plan view in FIG. 2a). This often leads to the jutting out of irregularly laid rings during tying or a failure in supplying circular coils demanded by users. Moving the sail itself for transferring a formed rod coil creates a considerable time lag before gathering the next coil of rod rings.
FIG. 3 is a graph that shows the condition of the inside diameter of wire rod coils made by the conventional method. While the aimed-for inside diameter is no smaller than 800 mm, in practice coils having an inside diameter smaller than 800 mm account for 12 percent of total coils produced.
Also, the descending sail 7 sometimes produces scratches on the internal surface of the coiled rods 9.